What is CVE-2026-40934?

CVE-2026-40934 is a medium-severity vulnerability in Jupyter Jupyter_server, classified under Insufficient Session Expiration. CVSS score: 6.8/10. Published 2026-05-05.

How severe is CVE-2026-40934?

Medium severity. CVSS v3 base score is 6.8 out of 10.

Vulnerability in Jupyter Jupyter_server

CVE-2026-40934

Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the secret used to sign authentication cookies is persisted to a static file at ~/.local/share/jupyter/runtime/jupyter_cookie_secret and is never r…

EPSS: 0.000 (5.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N.

Affected products

Jupyter Jupyter_server
Jupyter-server Jupyter_server — versions < 2.18.0

Weakness classification (CWE)

CWE-613 — Insufficient Session Expiration

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-40934?: CVE-2026-40934 is a medium-severity vulnerability in Jupyter Jupyter_server, classified under Insufficient Session Expiration. CVSS score: 6.8/10. Published 2026-05-05.
How severe is CVE-2026-40934?: Medium severity. CVSS v3 base score is 6.8 out of 10.